Downhole well applications, such as those used to extract crude oil from one or more production zones underneath the earth's surface, often require downhole power in order to operate components such as pressure and temperature sensors in the well. Current systems requiring downhole power include intelligent wells and permanent gauge installations where sensors or actuators are used in order to operate chokes and restrict fluid flow into a well at different levels for multiple zone production. Such systems are often necessary for control of pressure and flow from various zones.
Prior art downhole power generating systems include the use of an umbilical to power sensors and actuators from the surface. A typical umbilical comprises a protected electrical tethered line that can be used to deliver both power and data to the component as well as other downhole devices requiring power. In addition, wireless telemetry methods have proven useful for communications and general interfacing with such components and as a means of facilitating data transmission between the surface operator and the downhole device. Finally, batteries and battery packs can be used for short term power applications.
While such downhole power systems have proven useful, they do not meet the long term power needs of modern day production operations. For example, while the use of an umbilical is suitable for providing power and data communications to devices, the practical difficulties related to their installation and maintenance limits their long term usefulness. At the same time, umbilical systems can interfere with and obstruct the well, production tubing, and other down hole structures by restricting passage of tools and other components into the wellbore. The use of wireless telemetry with batteries has been contemplated, but such systems suffer from an inability to provide useful levels of power or sustain power over long periods of time.
Therefore, a long term downhole power solution that is suitable for use in a modem wellbore operation would provide numerous advantages.